You cannot modify the Hosts file or the Lmhosts file in Windows Vista and Windows 7

When you try to change the Hosts file or the Lmhosts file in Microsoft Windows Vista, or Windows 7, you may receive an error message that resembles either of the following.

Error message 1

Error message 2

This issue occurs even though you log on by using an account that has administrative credentials.

To work around this issue, follow these steps:

1. Click Start
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   , click All Programs, click Accessories, right-click Notepad, and then click Run as administrator.
   
   
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   If you are prompted for an administrator password or for a confirmation, type the password, or click Allow or Yes.
2. Open the Hosts file or the Lmhosts file, make the necessary changes, and then click Save on the Edit menu. If using Windows 7, you will need to click Save on the File menu.